Weight Brush Does nothing on any setting
If weight painting a vertex group in a mesh differently is not affecting how an armature deforms it, one of the following is probably true.

The vertex group has no bone with the same name to match with.
The armature modifier is disabled.
The armature modifier is set for “Bone envelopes” instead of “Vertex groups.”

Check for these. If not, make sure you were posing the correct bone.